Abstract Scope |
Nowadays, arc welding processes are still the most widely used joining technologies for metals. How to increase the efficiency of arc welding processes is always a key issue to meet the challenges faced in manufacturing industry. The increasing of welding speed and/or wire feed rate are effective ways to improve the arc welding efficiency. However, weld bead defects and other problems will occur when welding speed and/or wire feed rate are raised for conventional arc welding. To solve such problems, assistant energy sources like external electromagnetic or ultrasonic fields are integrated into conventional arc welding processes to control and change the heat transfer and fluid flow behaviors in weld pools and/or droplets, so that good process quality and weld joint quality are ensured even if the welding speed and/or wire feed rate are increased. Two examples are introduced here. One is the external compound magnetic field assisted GMAW for high-speed welding, another is the ultrasonic vibration assisted keyholing PAW for enhancing penetration capability. Advanced vision sensing systems are applied to observe the variations of the weld pool and metal transfer phenomena when secondary energy is exerted. Mathematical models of multi-physical fields are developed to elucidate the underlying mechanisms why the integrated external fields can improve the welding efficiency. |